State of the Planet

News from the Columbia Climate School

Peak Ecological Water

This graph charts the value of water provided by increasing supply  from various sources in a watershed against the loss in value of  ecological services provided by that water. From "Peak water limits  to freshwater withdrawal and use."

Earlier this month, Lakis blogged about the concept of peak water and the seminar that Peter Gleick gave at CWC on the topic. In addition, Gleick and Meena Palaniappan recently published a paper on the topic in the Proceedings of the National Academy of Sciences.

To me, one of the most interesting concepts that they introduce is ‘peak ecological water,’ which is the point at which so much water is being diverted from the environment for human use, that the ecosystem can no longer function normally. It can even get to the point that an ecosystem is irreversibly damaged, and there are estimates that humans already divert almost 50% of all accessible freshwater globally. According to their article, “Since 1900, half of the world’s wetlands have disappeared. The number of freshwater species has decreased by 50% since 1970, faster than the decline of species on land or in the sea. River deltas are increasingly deprived of flows due to upstream diversions, or receive water heavily contaminated with human and industrial wastes.”

So now we have a term for something that we’ve been watching occur all around us. The Dead Sea receives 5% of the water it used to naturally receive from the Jordan River – the other 95% is diverted for municipal and industrial use. Water supply to the Everglades is drastically reduced due to sugar production. Even if one doesn’t care about the health of the environment for its own sake, there is still reason to be concerned because a damaged ecosystem will not be able to provide the same services to humans that it has in the past.

Diminishing water flow in the Florida Everglades:

Source: Solcomhouse
Source: Solcomhouse

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